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Localization of an anti-CEA monoclonal antibody in colo-rectal carcinoma xenografts
Abstract:
A mouse monoclonal anti-CEA antibody (11.285.14) has been examined for tumour localization potential by assessing its distribution in immunodeprived mice with xenografts of human colon carcinoma cell lines HCT-8, HRT-18, HT-29, and LS174T and a xenograft (HRVB) established from a primary rectal carcinoma. With four carcinomas (HCT-8, HT-29, LS174T, and HRVB) preferential tumour localization of 125I anti-CEA was seen. Compared with 131I normal IgG1 localization indices of up to 4.4:1 were achieved. Up to 10% of the injected dose of 125I anti-CEA was present/g of tumour tissue and with the largest xenografts examined (3-4 g) up to 40% of the total body reactivity was localized in tumour tissue. The tumour localization of 131I labelled antibody was visualized by external gamma camera imaging. Overall antibody localization correlated with the CEA content of the xenografts and the fourth colon carcinoma xenograft (HRT-18) and an osteogenic sarcoma xenograft (791T), both with very low CEA levels, showed no localization of the monoclonal antibody.
Insights
This study investigated a mouse monoclonal antibody targeting carcinoembryonic antigen (CEA) for tumor localization. The antibody showed preferential tumor uptake in CEA-positive human colon carcinoma xenografts, demonstrating its potential for targeted cancer imaging.
Area of Science:
- Oncology
- Immunology
- Radiopharmaceuticals
Background:
- Carcinoembryonic antigen (CEA) is a tumor marker overexpressed in various carcinomas.
- Monoclonal antibodies targeting CEA have potential for cancer diagnosis and therapy.
- Assessing tumor localization is crucial for evaluating antibody-based imaging agents.
Purpose of the Study:
- To evaluate the tumor localization potential of a mouse monoclonal anti-CEA antibody (11.285.14).
- To determine the distribution of the anti-CEA antibody in xenografts of human colon and rectal carcinomas.
- To correlate antibody localization with CEA expression levels in tumors.
Main Methods:
- Xenografts of human colon carcinoma cell lines (HCT-8, HRT-18, HT-29, LS174T) and a rectal carcinoma (HRVB) were established in immunodeprived mice.
- 125I-labeled anti-CEA antibody and 131I-labeled normal IgG1 were administered.
- Biodistribution studies were performed to assess antibody localization.
- Gamma camera imaging was used to visualize antibody uptake in vivo.
- CEA content in xenografts was measured and correlated with antibody localization.
Main Results:
- Preferential tumor localization of 125I anti-CEA was observed in four out of five carcinoma xenografts (HCT-8, HT-29, LS174T, HRVB).
- Localization indices of up to 4.4:1 compared to normal IgG1 were achieved.
- Up to 10% of injected dose per gram of tumor tissue was found, with up to 40% of total body reactivity in large xenografts.
- Tumor localization directly correlated with CEA content; xenografts with low CEA levels showed no antibody uptake.
Conclusions:
- The mouse monoclonal anti-CEA antibody (11.285.14) demonstrates significant tumor localization potential in CEA-expressing human colon and rectal carcinoma xenografts.
- The antibody's localization is dependent on CEA expression levels, suggesting its utility for targeted imaging of CEA-positive tumors.
- External gamma camera imaging successfully visualized the tumor-specific uptake of the radiolabeled antibody.